High pressure apparatus operate by atomizing a mixture of compressed air and water into a mist in low temperature ambient air so that the droplets of water projected at high speed are transformed into ice crystals in contact with the cold air and fall to the ground as snow.
Such apparatus have been disclosed in French Pat. No. 1,337,141 and U.S. Pat. No. 2,676,471. The apparatus disclosed in these patents comprise separate pressurized water and compressed air supplies as well as a discharge nozzle assuring good snow flake distribution as a function of ambient atmospheric conditions. Adjustment is produced by replacing the nozzle or by varying the injected air and water pressures.
Now, for wet temperatures between -3.degree. and 0.degree. C. the amount of air required to transform a given quantity of water into snow is very large, and taking account of the wet temperature variations of the air and the rapidity of said variations, it is not possible with the apparatus disclosed in the aforementioned patents to manually assure a proper adjustment of the air/water mixture in this temperature zone, and this is all the more so because the temperature variations are usually unknown by the operators tending the snow guns.
Moreover, following the experiments carried out by the applicant, it has been found that the temperature of the water used is only responsible to a very smal extent for the total amount of air required for the transformation of one kiloram of water into snow, only the wet temperature of the ambient air has an effect thereon, which is determined as a function of the temperature of dry air and its humidity. Therefore, for each value of the wet temperature of the ambient air, the theoretical minimum value of the total number of cubic meters of air may be calculated for transforming one cubic meter of water into snow, i.e., the theoretical value of the minimum air/water ratio. It is to be noted that the minimum quantity of air required for assuring this transformation is in fact the overall volume of air concerned by this change of state, i.e., not only the amount of compressed primary air which is injected and expanded in the snow gun but also the amount of secondary air drawn at the exit of the snow gun which essentially depends on the shape, size and speed of the jet into the atmosphere.